1. Field of the Invention
The present invention relates to a spindle motor and a disk drive apparatus.
2. Description of the Related Art
A hard disk device or an optical disk device is equipped with a spindle motor for rotating a disk. The spindle motor includes a stationary unit fixed to a housing of the device and a rotary unit rotating together with a disk supported thereon. In the spindle motor, torque acting about a center axis is generated by magnetic flux generated between the stationary unit and the rotary unit, whereby the rotary unit is rotated with respect to the stationary unit.
A conventional spindle motor is disclosed in, e.g., Japanese Patent Application Publication No. 2011-114892. The spindle motor of Japanese Patent Application Publication No. 2011-114892 includes a base member, coils and a circuit substrate. Lead wires extending from the coils are led out via through-holes of the base member and are connected to the circuit substrate by solders (see claim 1 and paragraph [0027] of Japanese Patent Application Publication No. 2011-114892).
In the spindle motor disclosed in Japanese Patent Application Publication No. 2011-114892, the solder portions of the circuit substrate are arranged along a wall portion extending obliquely upward from a bottom portion of the base member, thereby reducing the axial thickness of the spindle motor (see paragraphs [0022] and [0027] and FIGS. 4 and 6 of Japanese Patent Application Publication No. 2011-114892).
In the spindle motor of this structure, solder portions are arranged along a circumferential direction. Thus, the circumferential length of the circuit substrate becomes larger. For that reason, if the circuit substrate is arranged along the unevenness of the base member, distortion is easily generated in the circuit substrate. Accordingly, there is a demand for a structure capable of restraining distortion of a circuit substrate even when solder portions are arranged along a circumferential direction.